If you will not use default Steam's DosBox and install Zandronum instead - yes, you will get full controller support.But you will need to map all keys yourself in Zandronum's options menu.Also, maybe singleplayer Doom is okay for gamepad, but once you come out to play online you will realize playing Doom on a gamepad is a really bad idea. Everyone is using keyboard and mouse online, so a single gamepad player will not be able to achieve high scores, and overall gameplay for a gamepad player will become a torture.So you have two choices - you play single only, but with a gamepad, or you play online with keyboard and mouse.Anyway, install Zandronum regardless of your choice. It will take about 15 minutes to set everything up and configure key bindings, display resolution, player name and color etc. but it will be definitely worth it.